Probably not what the OP is looking for but with Google Voice your messages are actually stored in your GV account. Your device just syncs with your GV account. If you lose your device, switch devices or even switch from one device OS to another you just load the GV app on the new device and sync. Messages are also accessible via any internet connected PC using the GV site (and you can send/receive through the site without your device). Of course, GV has its caveats.